The Map item is a data item that have lots of common with the Graph item. Similar to the Graph item, it allows the developers to present aggregated data by two hierarchical dimensions/groups. One of the dimensions - the GeoLocationGroup defines the geographical component of your data. The second one - the SeriesGroups hierarchy allows you to group your data in a hierarchical way and display one or more measures over the defined geographical reference. Like the other data items the Map item connects to a single data source and provides additional options for sorting and filtering the input data, binding, conditional formatting, etc.
As with the Graph item, it is important to carefully prepare and understand your data before you create your Map item, as this will help you design your report quickly and efficiently.
The GeoLocationGroup hierarchy defines the data points location in the Map series and acts the same way as the Graph's Category Group hierarchy. In case the report uses a Location provider to obtain the data point geographical coordinates from a web service, the GeoLocationMapGroup's grouping expression is used as a request parameter when calling the geocoding service. To achieve better geocoding results, the grouping expression should provide as more detailed request as possible, for example, concatenating a city name with a state/region name and a country name.
The ShapeMapGroup hierarchy is used only in ShapeMapSeries, which provide their own spatial data source, depending on the selected SourceType property. The geographical coordinates of the data points do not depend on this hierarchy, that's why it does not provide any geolocation properties.
The SeriesGroups hierarchy defines the series at runtime. For example, suppose you have a group by the Country field in the SeriesGroups hierarchy. The number of different countries will determine how many series will appear on the Map.
The Map item series displays aggregated data to visualize one or more measures. At runtime the intersection between the series group hierarchy members and the category group hierarchy members defines the data points in the series. Each data point's coordinates are obtained either directly from the data set (through the Latitude and Longitude properties, or using the Location property of the series' GeoLocationGroup, as explained above. The value of the data point is a measure for its size and is calculated by an expression, defined for its Size property.
The ShapeMapSeries, used in the Choropleth map, does not use the series group hierarchy the way it is used in the LocationMapSeries. The series grouping is not intended to be used in other way than having a static group, since the ShapeMapSeries defines its own grouping using properties, specific only to this series type (ColorData and ColorsCount). Therefore the ShapeMapSeries data points are created for each category group member and their coordinates are obtained via external source, depending on the series' SourceType property. The values of the data points determine their presentation colors and are a result of grouping the values into these ShapeMapSeries-specific groups, mentioned above.
When working with map series, it is often useful to have a way to determine the current data point coordinates and display them on a label or use them in conditional formatting rule. The evaluation engine provides a way to do so using the special expression "= Location". The evaluation result is an instance of type Location and its Longitude and Latitude properties can be accessed directly. Also, when the selected component in the report designer is MapSeriesBase, the Edit Expression dialog will include three Location entries in its Fields collection: Location, Location.Latitude and Location.Longitude.
When using ShapeMapSeries that obtain their geospatial information from a ShapeFile, the processing engine will automatically generate two virtual fields in the resulting composite data set: "Location.Latitude" and "Location.Longitude" that serve the same purpose - to use the coordinates of the data point centroid in expressions.